GB1568903A - Vehicle with dual braking systems - Google Patents

Description

PATENT SPECIFICATION

( 11) M ( 21) Application No 14058/77 ( 22) Filed 4 April 1977 3 ( 31) Convention Application No.

Ch 690888 ( 32) Filed 28 May 1976 in 0 ( 33) United States of America (US) úQ ( 44) Complete Specification published 11 June 1980 ) ( 51) INT CL ' B 60 T 7/00 7/02 7/12 _ 1 ( 52) Index at acceptance F 2 F 50 X A BC B 8 H 324 330 553 FC ( 54) VEHICLE WITH DUAL BRAKING SYSTEMS ( 71) We, J I CASE COMPANY, a Delaware Corporation of 700 State Street, Racine Wisconsin 53404, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement:-

The present invention relates generally to vehicles and more particularly to heavy duty construction vehicles having a crane supported on a turntable that is rotatable about an axis on the frame of the vehicle by drive means Such vehicles normally have a brake associated with the turntable to lock the turntable with respect to the frame when the crane is being operated.

In the past, there have been two types of brake systems which have been incorporated as "manufacturers installed equipment" for such vehicles At the time of manufacture, the vehicle or crane is equipped with either a free swinging or an automatic swinging brake system The automatic brake system incorporates a spring applied brake which is released by the hydraulic fluid that is used for operating the hydraulic swing motor In this system, the pressure rise on either side of the hydraulic swing motor is delivered to the brake cylinder to release the brake and, when the swing control valve is returned to neutral, hydraulic oil is bled from the brake cylinder to cause the spring to apply the brake.

In the free swinging system, the brake is again a spring applied brake which is released by hydraulic pressure that is controlled manually through the use of a control valve.

According to the present invention, a crane or like vehicle having a turntable rotatable about a fixed axis on a frame is provided with two types of braking system so that the operator has a choice of which system he desires to use The dual braking system is designed so that it can readily be incorporated into a crane with the addition of a minimum number 50 of parts.

More specifically, the dual braking system comprises a fluid circuit including first and second parallel conduits respectively leading from a pressurized fluid 55 source to one end of a brake cylinder with the first conduit having a first valve actuated in response to actuation of the drive motor for rotating the turntable on the fixed frame and a second manually oper 60 ated valve in the second conduit with a selector valve in both conduits for selectively blocking flow in one conduit while accommodating flow in the other conduit so that the brake may be released either 65 manually or in response to actuation of the drive motor.

The invention will now be further described by way of example with reference to the accompanying drawings in which: 70 Fig 1 is a general view of a vehicle of the type to which this invention relates and which may be in accordance with the present invention; and Fig 2 is a diagram of the fluid circuit 75 of a vehicle in accordance with the present invention.

Referring to Fig 1 a vehicle, generally shown at 10, carries or incorporates a crane The crane has a frame 12 which 80 is supported on a plurality of wheels 14.

A turntable 16 is mounted for rotation about a vertical axis 18 on frame 12 by a hydraulic motor 20 which has a gear box (not shown) secured thereto The 85 turntable -16 supports a housing 22 which encloses a power plant (not shown) and other suitable equipment required to operate the vehicle A crane 24 is supported on the housing 22 and is raised and lowered 90 1 568 903 1 568 903 by a fluid ram 26.

As indicated above, cranes of this type usually have some type of brake mechanism between the frame 12 and the turntable 16 to lock the turntable to the frame when the operator is working with the crane According to the present invention, the braking system is designed readily to be operated in either of two modes of operation.

As illustrated in Fig 2, the braking system includes a brake (not shown) that is applied and released by a fluid ram comprising a cylinder 32 and a piston rod 34 reciprocates in the cylinder 32 and is spring biassed to a first position by an internal spring 36 The piston rod 34 is connected to a multiple disc brake of the commercially known type that is now utilized in cranes of this type The multiple disc brake preferably cooperates with the output shaft of hydraulic motor 20 so that the hydraulic motor shaft is fixed when the brake is applied Preferably, the brake means is normally actuated by the force of spring 36 and is fluid pressure released by supplying fluid to the head end of cylinder 32.

Fig 2 shows the unique fluid circuit which allows the operator to choose which type of braking system is to be utilized for supplying fluid to cylinder 32 The fluid circuit includes a reservoir 40 for the fluid, which is preferably air but may be a hydraulic fluid An air compressor 42 is connected to the accumulator 40 and supplies fluid under pressure to a pressurized reservoir 44 The reservoir has an outlet conduit 46 connected thereto with two branch conduits 48 and 50 leading from conduit 46 The conduit 48 is connected to an inlet of a first valve 52 which has its outlet port connected to a selector valve 54 through a conduit 56 The outlet port of selector valve 54 is connected to the head end of cylinder 32 through a further conduit 58.

The valve 52 is also connected to the reservoir 40 through a conduit 60 having an adjustable restrictor 62 therein for a purpose that will be described later The valve 52 is a two position valve having a first position in which reservoir or pressurised fluid source 44 is connected to conduit 56 and a second position (illustrated in the drawings) wherein conduit 56 is connected to reservoir 40 through a restrictor 62.

The fluid circuit also has a further valve 64 having its inlet port connected to conduit 50 and an outlet port connected to selector valve 54 through a further conduit 66 The valve 64 is also connected to reservoir 40 through a conduit 68.

The valve 64 is a manually actuated valve which has the capability of varying the pressure output in response to the position of the valve spool Stated another way, the manually actuated valve 64 is a known type of variable pressure control 70 valve that has the capability of metering fluid flow from source 44 to selector valve 54.

Sumnmarizing the fluid circuit so far described, conduits 46, 48, 56 and 58 define 75 a first flow path having control valve 52 therein Control valve 52 is preferably moved from the position illustrated in response to actuation of the drive motor or drive means 20 and is returned to 80 the position illustrated when the drive means is in a neutral condition This may be accomplished by a cam that is connected to the linkage for the control valve that operates the hydraulic motor 85 The fluid circuit also has a second flow path consisting of conduits 46, 50 and 66 having manually actuated valve 64 therein.

Selector valve 54 is a two position valve which connects conduit 56 to conduit 58 90 in one position and connects conduit 66 to conduit 58 in the second position Thus, the respective conduits define two parallel flow paths from pressurised fluid source 44 to selector valve 54 95 If the operator wants manual control for the braking operation, he positions selector valve 54 to the position illustrated in the drawings wherein manually actuated valve 64 is connected to conduit 58 so 100 that the operator has manual control of the supply of pressurised fluid to brake cylinder 32 to release the brake.

Alternatively, if an operator wishes to use an automatic braking arrangement 105 wherein the brake is released when the drive motor is actuated, it is only necessary to move selector valve 54 from the position illustrated to a second position wherein conduit 56 is connected to con 110 duit 58 In this position, the rate at which fluid is forced from cylinder 32 is determined by the adjustment of restrictor valve 62 so that the operator can readily set the rate of brake release in this mode of 115 operation.

Claims (6)

WHAT WE CLAIM IS:

1 A vehicle having a turntable rotatable about a fixed axis on a frame by drive means and having a fluid-released brake 120 located between the frame and the turntable, and including a fluid circuit for supplying fluid under pressure to the brake comprising a reservoir, a pressurized fluid source connected to the reservoir, a first 125 conduit connecting the source to the brake, and having a first valve actuated in response to actuation of the drive means, a second conduit connecting the source to the brake, and having a second manually 130 1 568 903 actuated valve therein, and a selector valve being present in both the first and second conduits for selectively blocking flow in one conduit while allowing flow in the other conduit so that the brake may be released either manually or in response to actuation of the drive means.

2 A vehicle as claimed in claim 1, in which the first valve is a two position valve connecting the source to the brake in a first position and connecting the brake to the reservoir in a second position a restrictor being located in the conduit between the brake and reservoir to restrict fluid flow from the brake to the reservoir.

3 A vehicle as claimed in either claim 1 or 2 in which the selector valve is located in the conduit between the brake and the first and second valves 20

4 A vehicle as claimed in any of the preceding claims, in which the manually actuated valve is capable of metering flow from the said source to the brake.

A vehicle as claimed in any of the 25 preceding claims, in which the said fluid is air.

6 A vehicle substantially as hereinbefore described with reference to the accompanying drawings 30 For the Applicants LLOYD WISE, BOULY & HAIG, Chartered Patent Agents, Norman House, 105-109 Strand, London, WC 2 R OAE.

Printed for Her Majesty's Stationery Office by The Tweeddale Press Ltd, Berwick-upon-Tweed, 1980.

Published at the Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.